Lisa: Who is that in you photo?
Maggie: Oh no! I didn't see that before. I've no idea who that is.
Lisa: That must be a photobomb!
Photobomb - English slang for someone jumping into the background or frame of a picture uninvited.
This slang can also be used as a verb. Stop photobombing my photos!
It's a classic photo! Do you have any other examples of photobombing?
That's awesome photobombing!